The production of metal alloys is particularly challenging when the starting components used have high melting point differences. In such cases it may happen that the starting component with the lower melting point is vaporized, if the temperature required for melting the other component is set.
From the prior art methods are known which introduce a solid body of the higher melting material into a melt of the lower melting material. The higher melting material is then slowly absorbed by the melt. This process is very time consuming and thus costly. Moreover, the lower melting material is maintained for a long time at a high temperature, which promotes the evaporation.
An alternative method includes the simultaneous compacting of corresponding metal powders and then sintering the compact. This method is disadvantageous due to the grinding process and the energy required for sintering.
DE 692 16 171 T2 describes a method of melting titanium aluminide alloys in which the oxygen absorption of the alloy should be minimized during the melting process in a calcium oxide ceramic crucible. In order to achieve this, niobium is added to the alloy. In the method described therein it is provided to first melt the components aluminum and niobium among others. Subsequently the titanium is added to the melt. Moreover, an alternative method is described in which the starting metals are added in a solid form into the crucible. Herein, titanium is added as a solid onto the other components. In this way the effect should be achieved that the titanium melts as the last component and is therefore exposed to the ceramic crucible only for a very short time. The batch is heated using conventional methods such as induction, plasma, arc or resistance heaters. The method described in this document operates under atmospheric pressure and optionally under a protective gas such as argon. The melting point of titanium at atmospheric pressure is approximately 1660° C., that of aluminum only 660° C. Thus, the aluminum melts first. However, aluminum boils only at 2470° C. Consequently, here the problem of evaporation of the low melting metal does not arise. The oxygen contents of the alloys thus produced are well above 400 ppm.